Device for the supply of liquid under pressure to an element at a rotating axis

ABSTRACT

A device for the supply of a liquid under pressure to a flow passage ( 13 ) in a member in a shaft suspension unit ( 1 ) of a centrifugal separator, which has a stationary casing ( 3 ) and a unit, which is resiliently and oscillation dampingly suspended in the casing ( 3 ) by at least one elastical element ( 10 ), the member forming a part of the composed unit. To be able to supply liquid to the member in a sample manner with a certain controllable flow which is made sure under overpressure a first supply channel portion ( 19 ) is connected to a liquid source ( 16 ) for the supply of liquid under pressure extending through the stationary casing ( 3 ). To the first supply channel portion ( 19 ) there is connected a second supply channel portion ( 21 ) extending through the elastical element ( 10 ). A third supply channel portion ( 23 ) is connected to the second supply channel portion ( 21 ), extending through the non-rotatable part of the composed unit and having an outlet opening ( 24 ) in the flow passage ( 13 ).

FIELD OF THE INVENTION

The present invention concerns a device for the supply of a liquid underpressure to a member having at least one flow passage, through whichthis liquid is passing and which is kept filled up with the liquid, in ashaft suspension device of a centrifugal separator. The suspensiondevice has a stationary casing and a unit composed of parts, which arerotatable around a rotational axis, and non-rotatable parts. The unit isresiliently supported in the casing by means of at least one elasticalelement in such a way that the unit during operation is admitted tooscillate relative to the casing while it is influenced by the elasticalelement with an essentially radially inwardly directed spring forceunder damping influence by the elastical element on the oscillatingmovements of the unit. The member forms a part of the composed unit.

BACKGROUND OF THE INVENTION

In centrifugal separators provided with a shaft suspension device ofthis kind the elastical element acts with a well defined radiallyinwardly directed spring force, which during operation strives to bringthe composed unit back to a central position and damps effectively theoscillating movements of it, which can be very critical during thepassage of critical number of revolutions or when heavy unbalances occurduring operation. Furthermore, bearing devices of this kind often arecheaper than alternative possible solutions.

In some centrifugal separators you need to be able to supply duringoperation a liquid under pressure to a member forming a part of thecomposed unit. One example when you need this is centrifugal separators,which demand an effective cooling of the bearings. Another example iscentrifugal separators, in which a gap between a stationary part and apart oscillating during operation is sealed by means of a liquid gapsealing. A third example is centrifugal separators journally supportedhydraulically, in which rotating parts are supported by a carrying oilfilm. However, in this case the flow passage has to be throw flown by asmall amount of oil, which corresponds to the amount of oil, whichleaves the hydraulic bearing through leakage or the like.

SUMMARY OF THE INVENTION

The object of the present invention is to accomplish a device for thesupply of the liquid under pressure to a member in a shaft suspensionunit of a centrifugal separator of the kind initially described, themember having at least one flow passage, which during operation is throwflown by and is kept filled with this liquid, which makes it possible tosupply liquid to the member in a simple manner with a certaincontrollable flow, which is made sure under overpressure.

According to the present invention this is accomplished by providing adevice for the supply of liquid of the kind initially described with afirst supply channel portion, which is connected to a liquid source forthe supply of liquid under pressure, and which extends through thestationary casing, a second supply channel portion, which hydraulicpressure transmittingly is connected to the first supply channelportion, and which extends through the elastical element, and a thirdsupply channel portion, which hydraulic pressure transmittingly isconnected to the second supply channel portion, and which extendsthrough a non-rotatable part in the composed unit, and which has anoutlet opening in said flow passage.

Hereby, the elastical element already present in the shaft suspensiondevice of the centrifugal separator for another purpose also is used toform an elastical supply channel portion, which makes it possible in avery simple manner hydraulic pressure transmittingly connect a supplychannel portion extending through the casing, which is stationary (i.e.is not rotating and is not oscillating with the oscillating movements ofthe composed unit), with a supply channel portion, which extends throughthe non-rotating part of the composed oscillating unit.

In another embodiment of the invention there is formed in the stationarycasing an inlet chamber, which is sealed off by means of the elasticalelement, which is annularly shaped and surrounds the rotation axis,between a part, which is connected to the casing and a part, which isconnected to the non-rotatable part of the composed unit, the firstchannel portion having an outlet opening in the inlet chamber and thesecond channel portion having an inlet opening in the inlet chamber.

In a preferred variant of this embodiment of the invention the devicecomprises at least two annular and the axis surrounding elasticalelements, which sealingly bear against a stationary part connected tothe casing and against a non-rotatable annular part connected to thecomposed unit, the non-rotatable annular part extending between thesecomponents.

Suitably, the second channel portion is arranged in the non-rotatableportion connected to the composed unit.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention will be described more in detail withreference to the attached drawings, on which

FIG. 1 schematically shows an axial section through a shaft suspensiondevice in a centrifugal separator, which is provided with an embodimentof a device for the supply of liquid to the same according to thepresent invention,

FIG. 2 schematically shows an axial section through a shaft suspensiondevice in a centrifugal separator, which is provided with anotherembodiment of a device for the supply of liquid to the same according tothe present invention, and

FIG. 3 schematically shows an axial section through a shaft suspensiondevice in a centrifugal separator, which is provided with the thirdembodiment of a device for the supply of liquid to the same according tothe present invention.

DETAILED DESCRIPTION

The shaft suspension device shown in the FIG. 1 supports the shaft 2 ofthe centrifugal separator. The shaft suspension device 1 has astationary casing 3, which surrounds the shaft 2. In the axial endportions of the casing 3 two openings 4 and 5, respectively, arearranged, through which the shaft 2 extends. On one axial end of theshaft a rotor 6 is fixedly mounted and on the other axial end of it abelt drive 7 is arranged for the driving of the shaft 2. The shaft 2 isjournally supported in a lower bearing 8, which essentially is directlyconnected to the stationary casing 3, and in an upper bearing 9, whichis connected to the stationary casing 3 via an annular elastical element10. The elastical element 10 abuts against a non-rotatable part 11 ofthe composed unit, which is resiliently suspended in the casing 3 bymeans of the elastical element 10. The non-rotatable part 11 consists inthis embodiment of the first annular sealing element 11, which extendsaround the shaft 2 and connects the elastical element 10 to the upperbearing 9 at the same time as it constitutes the bearing housing for theupper bearing 9. Radially inside the first sealing element 11 there isarranged a second annular sealing element 12, which is connected to theshaft 2 around the same and together with the first sealing element 11forms an annular flow passage 13 surrounding the shaft 2.

The sealing elements 11 and 12 divide a space inside the casing 3 in twodepartments 14 and 15, which are connected to one opening each 4 and 5,respectively. To prevent the air or gas volumes from communicating witheach other during operation via the through passage 13 this is arrangedto be kept filled up with liquid.

For this purpose a liquid source 16 for oil is arranged in the lowerpart of the shaft suspension device 1, to which a conduit 17 isconnected. This conduit is provided with a pump 18 and is connected to afirst supply channel portion 19, which opens in a closed chamber 20radially outside the first sealing element 11. In the elastical element10 a second supply channel portion 21 is arranged, which has an inletopening 22 in the closed chamber 20 and is thus hydraulical pressuretransmittingly connected to the first supply channel portion 19 via theclosed chamber 20. In the first sealing element 11 a third supplychannel portion 23 is arranged, which hydraulical pressuretransmittingly is connected to the second supply channel portion 21, andwhich has an outlet opening 24 in a recess 25, which is formed in acentral portion of the first sealing element 11. The recess 25 surroundsthe shaft and is open towards the second sealing element 12. The supplychannel portions 19, 21 and 23 are through flown during operation by oilunder pressure, which fills up the flow passage 13. Thereby, the oil inthe flow passage 13 prevents effectively air or other gas to flowbetween the two departments 14 and 15.

The amount of oil, which flows out of the flow passage 13 in directiontowards and out into the one or the other of the two departments 14 and15, is depending on how long and narrow the flow passage 13 is indirection towards the one department 14 in relation to how long andnarrow the flow passage 13 is in direction towards the other department15. Elements which rotate with the shaft in the one department 14creates an air circulation, which entrains oil, which flows into thisdepartment 14, and brings a portion of this oil to flow towards andthrough the bearing present in this department, the second bearing 9.The oil, which has passed through the upper bearing 9 is collected in acollecting grove 26, which opens radially inwardly and is connected to areturn conduit 27, through which collected oil flows back to the liquidsource 17 via a liquid seal 28, which prevents air or gas circulationthrough the return conduit 27. The most of the oil, which flows outthrough the one department 14 is conducted directly to the liquid source17 via a by-pass conduit 29, which in the shown example is connected tothe return conduit 27.

Oil is supplied to the flow passage 13 at such a high pressure duringoperation that the flow passage 13 remains filled up at the pressuredifferences which are prevailing between the two departments 14 and 15.In certain cases capillary forces can be sufficient to keep the flowpassage 13 filled up whereas in other cases a substantially higherpressure is needed to keep the flow passage 13 filled up with oil.

In the example shown in FIG. 1 the departments 14 and 15 communicatewith the atmosphere surrounding the shaft suspension device 1 via therespective opening 4 and 5 but it is quite possible within the scope ofthe present invention that they communicate via adherent opening with amore or less closed chamber.

The shaft suspension device shown in FIG. 2 differs from the shaftsuspension device 1, shown in FIG. 1, by the fact that the elasticalelement is formed by two co-operating and shaft surrounding elasticaland annular components 30 and 31, in which the composed unit isresiliently suspended in the casing 3, and by the fact that is providedwith a first sealing element 32, which extends radially between the twoelastical components 30 and 31. In this sealing element 32 there isarranged a supply channel portion 33, which extends radially between thetwo elastical components 30 and 31, and which has an inlet opening 34 inthe closed chamber 20 and has an outlet opening 35 in a recess 36, whichis formed in a central portion of this sealing element 32. The supplychannel portion 33 is hydraulic pressure transmittingly connected to thefirst supply channel portion 19 via the closed chamber 20, andconstitutes the second as well as the third supply channel portion.

Other parts of this shaft suspension device is the same as thecorresponding parts of the shaft suspension device shown in FIG. 1 andhas obtained the same reference number.

In the two shaft suspension devices shown in FIGS. 1 and 2 the member,which is to be supplied with liquid, consists of a liquid gap sealing, aflow gap being constituted by the gap, which during operation shall bekept filled up with liquid to maintain the sealing function.

In the shaft suspension device shown in FIG. 3 the member, which is tobe supplied with liquid, instead is constituted by a cooling device 37,whereas said flow passages are constituted by channels 38 for a coolingliquid arranged in the cooling device 37. The cooling device in thisshaft suspension device constitutes a non-rotatable part of the composedunit at the same time as it constitutes bearing housing for the upperbearing 9. The cooling liquid, which has passed through the channels 38,flows out into the department 15 and falls down in and is collected inthe liquid source 16.

The other parts in this shaft suspension device are also the same ascorresponding parts of the shaft suspension device shown in FIG. 1 andhave obtained the same reference numbers.

What is claimed is:
 1. A device which supplies a liquid under pressure to a member having at least one flow passage (13), through which this liquid is passing and which is kept filled up with the liquid, in a shaft suspension device (1) of a centrifugal separator having a shaft, the shaft suspension device having a stationary casing (3) and a unit being composed of parts, which are rotatable around a rotational axis, and non-rotatable parts, and being resiliently supported in the casing (3) by means of at least one elastical element (10) in such a way that the unit during operation is allowed to oscillate relative to the casing while it is influenced by the elastical element (10) with an essentially radially inwardly directed spring force which causes a damping influence by the elastical element (10) on the oscillating movements of the unit, said member forming a part of the composed unit, comprising a first supply channel portion (19), which is connected to a liquid source (16) for the supply of said liquid under pressure, and which extends through the stationary casing (3), a second supply channel portion (21), for transmitting said liquid under pressure, is connected to the first supply channel portion (19), and extends through the elastical element (10), and a third supply channel portion (23), for transmitting said liquid under pressure, is connected to the second supply channel portion (21), and extends through a non-rotatable part in the composed unit, and has an outlet opening (24) in said flow passage (13).
 2. A device according to claim 1, further comprising an inlet chamber (20), which is formed in the stationary casing (3) and sealed off by means of the elastical element (10), which is annular and surrounds the rotational axis, between a part which is connected to the casing (3) and a part, which is connected to a non-rotatable part of the composed unit, the first channel portion (19) having an outlet opening in the inlet chamber (20) and the second channel portion (21) having an inlet opening (22) in the inlet chamber (20).
 3. A device according to claim 2, wherein that the elastical element is formed by two co-operating elastical and annular components (30,31) surrounding the shaft, in which the composed unit is resiliently suspended in the casing (3), and which sealingly bear against a stationary part connected to the casing and against a non-rotatable annular part connected to the composed unit, the non-rotatable annular part extending between these components.
 4. A device according to claim 3, wherein that the second channel portion (21) is arranged in the non-rotatable annular part, which is connected to the composed unit.
 5. A device according to claim 3 or 4, wherein that the non-rotatable annular part, which is connected to the composed unit extends essentially radially between the two elastical annular components (30, 31).
 6. A device according to claim 1, wherein the liquid consists of oil.
 7. A device according to claim 1, wherein said member comprising a liquid gap sealing device.
 8. A device according to claim 1, wherein said member comprising a cooling device, said flow passages comprising channels (38) for a cooling liquid. 